KR102497439B1 - Ferritic stainless steel with improved ridging resistance and its manufacturing method - Google Patents

Ferritic stainless steel with improved ridging resistance and its manufacturing method Download PDF

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KR102497439B1
KR102497439B1 KR1020200171165A KR20200171165A KR102497439B1 KR 102497439 B1 KR102497439 B1 KR 102497439B1 KR 1020200171165 A KR1020200171165 A KR 1020200171165A KR 20200171165 A KR20200171165 A KR 20200171165A KR 102497439 B1 KR102497439 B1 KR 102497439B1
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stainless steel
ferritic stainless
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hardening
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KR20220081556A (en
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공정현
이문수
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주식회사 포스코
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Priority to PCT/KR2021/011464 priority patent/WO2022124526A1/en
Priority to EP21903573.0A priority patent/EP4261319A1/en
Priority to US18/265,345 priority patent/US20240035134A1/en
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    • C21D2211/00—Microstructure comprising significant phases
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Abstract

본 명세서에서는 내리징성이 향상된 페라이트계 스테인리스강에 대하여 개시한다.
개시되는 내리징성이 향상된 페라이트계 스테인리스강의 일 실시예에 따르면, 중량%로, C: 0.001 내지 0.3%, Si: 0.01 내지 1.0%, Mn: 0.1 내지 3.0%, Cr: 10 내지 15%, N: 0.001 내지 0.3%, P: 0.03% 이하, Ni: 1.0% 이하, Cu: 1.0% 이하, Al: 1.0% 이하, Mo: 0.003% 이하, Ti: 1.0% 이하 나머지 Fe 및 기타 불가피한 불순물을 포함하고,
하기 식(1)로 표현되는 γS가 6 이상을 만족한다.
식(1): γS = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178
(여기서, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al 및 N는 각 원소의 함량(중량%)을 의미한다)In the present specification, ferritic stainless steel with improved resistance to hardening is disclosed.
According to one embodiment of the disclosed ferritic stainless steel with improved hardening resistance, in weight percent, C: 0.001 to 0.3%, Si: 0.01 to 1.0%, Mn: 0.1 to 3.0%, Cr: 10 to 15%, N: 0.001 to 0.3%, P: 0.03% or less, Ni: 1.0% or less, Cu: 1.0% or less, Al: 1.0% or less, Mo: 0.003% or less, Ti: 1.0% or less Fe and other unavoidable impurities,
γ S represented by the following formula (1) satisfies 6 or more.
Equation (1): γ S = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178
(Here, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al and N mean the content (% by weight) of each element)

Figure 112020133442788-pat00001
Figure 112020133442788-pat00001

Description

내리징성이 향상된 페라이트계 스테인리스강 및 그 제조방법{Ferritic stainless steel with improved ridging resistance and its manufacturing method}Ferritic stainless steel with improved ridging resistance and its manufacturing method

본 발명은 페라이트계 스테인리스강 및 그 제조방법에 관한 것으로, 보다 상세하게는 내리징성이 향상된 페라이트계 스테인리스강 및 그 제조방법에 관한 것이다.The present invention relates to ferritic stainless steel and a method for manufacturing the same, and more particularly, to a ferritic stainless steel with improved resistance to hardening and a method for manufacturing the same.

일반적으로 스테인리스강은 화학성분이나 금속조직에 따라 분류된다. 금속조직에 따를 경우, 스테인리스강은 오스테나이트계(300계), 페라이트계(400계), 마르텐사이트계, 이상계로 분류된다.In general, stainless steel is classified according to its chemical composition or metal structure. According to the metal structure, stainless steel is classified into austenitic (300 series), ferritic (400 series), martensitic, and ideal type.

이 중 페라이트계 스테인리스강은 고가의 합금원소가 적게 첨가되어, 오스테나이트계 스테인리스강에 비하여 가격 경쟁력이 높은 강재이다. 페라이트계 스테인리스강은 표면광택, 드로잉성 및 내산화성이 양호하여 주방용품, 건축 외장재, 가전제품, 전자부품 등에 널리 사용되고 있다. 특히, 페라이트계 스테인리스강은 외장용으로 사용되는 경우 고품질의 표면 광택도가 요구되는 강종이다.Among them, ferritic stainless steel is a steel material having a high price competitiveness compared to austenitic stainless steel because a small amount of expensive alloying elements are added. Ferritic stainless steel has good surface gloss, drawability, and oxidation resistance, and is widely used in kitchen utensils, building exterior materials, home appliances, and electronic parts. In particular, ferritic stainless steel is a type of steel that requires high-quality surface gloss when used for exterior purposes.

하지만, 페라이트계 스테인리스강은 딥드로잉과 같은 성형가공 시 압연방향에 평행하게 줄무늬 모양의 리징(Ridging) 결함이 발생하는 문제점을 가지고 있다. 이러한 리징 결함은 제품의 외관을 나쁘게 하고, 리징 결함이 심하게 발생할 경우에는 성형 후에 연마공정이 추가되기 때문에 제조단가가 높아진다.However, ferritic stainless steel has a problem in that stripe-shaped ridging defects occur in parallel to the rolling direction during forming processing such as deep drawing. Such leasing defects deteriorate the appearance of the product, and when severe leasing defects occur, the manufacturing cost increases because a polishing process is added after molding.

리징의 발생원인은 아직까지 명확하게 밝혀지지 않았지만 대개 다음과 같이 알려져 왔다. 슬라브 주조 시 생성되는 주상정(Columnar grains)은 주로 {001}//ND 집합조직을 갖게 되는데, 이 조직은 열연 이후에도 재결정이 잘 일어나지 않아 밴드 조직(band structure)이나 콜로니(colony)조직으로 남게 된다.The cause of leasing has not yet been clearly identified, but it has been known as follows. Columnar grains generated during slab casting mainly have a {001}//ND texture, which does not recrystallize well even after hot rolling, leaving a band structure or a colony structure. .

특히, 대부분의 페라이트계 스테인레스강은 주조에서부터 냉연 소둔 공정에 이르기까지 상변태가 없어 {001}//ND 집합조직을 제거하기 더 어렵다. 따라서, {001}//ND 집합조직은 최종 냉연 후에도 압연방향으로 긴 콜로니 조직으로 남게 된다. 남게된 콜로니 조직은 주변의 다른 집합조직을 갖는 조직에 비해 상대적으로 낮은 소성이방성(R값)을 나타낸다. 이러한 소성이방성의 차이는 성형 가공시 두 조직 간의 소성 불균형을 야기하여, 페라이트 스테인리스강에 리징 결함을 발생시킨다.In particular, most ferritic stainless steels have no phase transformation from casting to cold rolling annealing, making it more difficult to remove the {001}//ND texture. Therefore, the {001}//ND texture remains as a long colony structure in the rolling direction even after final cold rolling. The remaining colony tissue exhibits a relatively low plasticity (R value) compared to the tissue having other surrounding textures. This difference in plastic anisotropy causes a plasticity imbalance between the two structures during molding, causing ridging defects in ferritic stainless steel.

리징 결함을 해결하기 위해, 종래에는 극한 저온에서의 열간압연, 이속압연 및 냉연 재압 등 다양한 제조방법이 제안되었다. 그러나, 종래 제안된 제조방법은 현장 적용이 어렵고 제조원가를 상승시켜 제품의 생산성을 저하시키는 문제가 있다.In order to solve the ridging defect, conventionally, various manufacturing methods such as hot rolling at extremely low temperatures, two-speed rolling, and cold rolling repressing have been proposed. However, the conventionally proposed manufacturing method has a problem in that it is difficult to apply to the field and increases the manufacturing cost, thereby reducing the productivity of the product.

한국 공개특허공보 제10-2001-0018940호 (공개일자: 2006년03월15일)Korean Patent Publication No. 10-2001-0018940 (published on March 15, 2006)

본 발명은 페라이트계 스테인리스강 및 그 제조방법에 관한 것으로, 내리징성이 향상된 페라이트계 스테인리스강 및 그 제조방법을 제공하고자 한다.The present invention relates to ferritic stainless steel and a method for manufacturing the same, and to provide a ferritic stainless steel with improved resistance to hardening and a method for manufacturing the same.

본 발명의 일 실시예에 따른 내리징성이 향상된 페라이트계 스테인리스강은 중량%로, C: 0.001 내지 0.3%, Si: 0.01 내지 1.0%, Mn: 0.1 내지 3.0%, Cr: 10 내지 15%, N: 0.001 내지 0.3%, P: 0.03% 이하, Ni: 1.0% 이하, Cu: 1.0% 이하, Al: 1.0% 이하, Mo: 0.003% 이하, Ti: 1.0% 이하 나머지 Fe 및 기타 불가피한 불순물을 포함하고,Ferritic stainless steel with improved hardening resistance according to an embodiment of the present invention contains, by weight, C: 0.001 to 0.3%, Si: 0.01 to 1.0%, Mn: 0.1 to 3.0%, Cr: 10 to 15%, N : 0.001 to 0.3%, P: 0.03% or less, Ni: 1.0% or less, Cu: 1.0% or less, Al: 1.0% or less, Mo: 0.003% or less, Ti: 1.0% or less, including the remaining Fe and other unavoidable impurities, ,

하기 식(1)로 표현되는 γS가 6 이상이다.γ S represented by the following formula (1) is 6 or more.

식(1): γS = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178Equation (1): γ S = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178

(여기서, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al 및 N는 각 원소의 함량(중량%)을 의미한다)(Here, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al and N mean the content (% by weight) of each element)

또한, 본 발명의 일 실시예에 따르면, 상기 페라이트계 스테인리스강은 페라이트 결정립 크기가 15㎛ 이하를 만족할 수 있다.In addition, according to one embodiment of the present invention, the ferritic stainless steel may satisfy a ferrite grain size of 15 μm or less.

또한, 본 발명의 일 실시예에 따르면, 상기 페라이트계 스테인리스강은 1.0mm 이하의 두께에서 15% 인장한 후 측정한 리징 높이(Wt)가 10㎛ 이하를 만족할 수 있다.In addition, according to an embodiment of the present invention, the ferritic stainless steel may have a ridging height (Wt) of 10 μm or less measured after stretching by 15% at a thickness of 1.0 mm or less.

본 발명의 또 다른 실시예에 의하면, 내리징성이 향상된 페라이트계 스테인리스강 제조방법은 중량%로, C: 0.001 내지 0.3%, Si: 0.01 내지 1.0%, Mn: 0.1 내지 3.0%, Cr: 10 내지 15%, N: 0.001 내지 0.3%, P: 0.03% 이하, Ni: 1.0% 이하, Cu: 1.0% 이하, Al: 1.0% 이하, Mo: 0.003% 이하, Ti: 1.0% 이하 나머지 Fe 및 기타 불가피한 불순물을 포함하고, 하기 식(1)로 표현되는 γS가 6 이상인, 슬라브를 1050 내지 1250℃로 재가열하는 단계; 상기 재가열된 슬라브를 열간압연 하는 단계; 및 상기 열간압연재를 냉간압연하고, 냉연소둔하는 단계;를 포함하고, 재가열 단계에서, 온도 T에서의 오스테나이트 중량%로 정의되는 γWt(T)가 하기 식(2)를 만족하도록 제어한다.According to another embodiment of the present invention, the ferritic stainless steel manufacturing method with improved resistance to hardening contains, by weight, C: 0.001 to 0.3%, Si: 0.01 to 1.0%, Mn: 0.1 to 3.0%, Cr: 10 to 15%, N: 0.001 to 0.3%, P: 0.03% or less, Ni: 1.0% or less, Cu: 1.0% or less, Al: 1.0% or less, Mo: 0.003% or less, Ti: 1.0% or less, the remaining Fe and other unavoidable Reheating the slab at 1050 to 1250 ° C. containing impurities and having γ S of 6 or more represented by the following formula (1); hot rolling the reheated slab; And cold rolling and cold rolling annealing the hot rolled material; including, in the reheating step, γ Wt (T) defined as austenite weight% at a temperature T is controlled to satisfy the following formula (2) .

식(1): γS = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178Equation (1): γ S = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178

(여기서, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al 및 N는 각 원소의 함량(중량%)을 의미한다)(Here, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al and N mean the content (% by weight) of each element)

식(2): γWt(1200℃) ≥ 19%Equation (2): γ Wt (1200 ° C) ≥ 19%

또한, 본 발명의 일 실시예에 따르면, 상기 재가열 단계에서, 하기 식(3)을 만족할 수 있다.In addition, according to an embodiment of the present invention, in the reheating step, the following equation (3) may be satisfied.

식(3): γS*γWt (1200℃) ≥ 114Equation (3): γ S * γ Wt (1200 ° C) ≥ 114

또한, 본 발명의 일 실시예에 따르면, 상기 열간압연은 700 내지 950℃에서 수행될 수 있다.In addition, according to one embodiment of the present invention, the hot rolling may be performed at 700 to 950 ℃.

또한, 본 발명의 일 실시예에 따르면, 상기 열간압연 후, 600 내지 900℃에서 열연 소둔하는 단계를 더 포함할 수 있다.In addition, according to one embodiment of the present invention, after the hot rolling, a step of hot rolling annealing at 600 to 900 ° C. may be further included.

본 발명은 합금성분 및 성분 관계식뿐만 아니라, 재가열 및 열간압연 조건을 최적화함으로써 균일한 표면 품질을 갖는, 내리징성이 향상된 페라이트계 스테인리스강 및 그 제조방법을 제공할 수 있다. The present invention can provide a ferritic stainless steel having uniform surface quality and improved resistance to hardening and a manufacturing method thereof by optimizing not only alloy components and component relations, but also reheating and hot rolling conditions.

도 1a는 JMatPro를 이용한 실시예 3의 γWt(1200℃)를 포함한 상태도이다.
도 1b는 JMatPro를 이용한 실시예 10의 γWt(1200℃)를 포함한 상태도이다.
도 1c는 JMatPro를 이용한 비교예 1의 γWt(1200℃)를 포함한 상태도이다.
도 1d는 JMatPro를 이용한 비교예 6의 γWt(1200℃)를 포함한 상태도이다.
도 2a는 IQ(Image Quality) map으로 조사한 실시예 3의 열연 미세조직이다.
도 2b는 IQ(Image Quality) map으로 조사한 실시예 10의 열연 미세조직이다.
도 2c는 IQ(Image Quality) map으로 조사한 비교예 1의 열연 미세조직이다.
도 2d는 IQ(Image Quality) map으로 조사한 비교예 6의 열연 미세조직이다.
도 3a는 IPF(Inverse Pole Figure) map으로 조사한 실시예 3의 열연 미세조직이다.
도 3b는 IPF(Inverse Pole Figure) map으로 조사한 실시예 10의 열연 미세조직이다.
도 3c는 IPF(Inverse Pole Figure) map으로 조사한 비교예 1의 열연 미세조직이다.
도 3d는 IPF(Inverse Pole Figure) map으로 조사한 비교예 6의 열연 미세조직이다.
도 4a는 실시예 3의 냉연소둔 후 표면 미세조직을 나타낸 사진이다.
도 4b는 실시예 10의 냉연소둔 후 표면 미세조직을 나타낸 사진이다.
도 4c는 비교예 1의 냉연소둔 후 표면 미세조직을 나타낸 사진이다.
도 4d는 비교예 6의 냉연소둔 후 표면 미세조직을 나타낸 사진이다.Figure 1a is a phase diagram including γ Wt (1200 ℃) of Example 3 using JMatPro.
Figure 1b is a phase diagram including γ Wt (1200 ℃) of Example 10 using JMatPro.
Figure 1c is a state diagram including γ Wt (1200 ℃) of Comparative Example 1 using JMatPro.
Figure 1d is a state diagram including γ Wt (1200 ℃) of Comparative Example 6 using JMatPro.
Figure 2a is a hot-rolled microstructure of Example 3 investigated by IQ (Image Quality) map.
Figure 2b is a hot-rolled microstructure of Example 10 investigated by IQ (Image Quality) map.
Figure 2c is a hot-rolled microstructure of Comparative Example 1 examined by IQ (Image Quality) map.
Figure 2d is a hot-rolled microstructure of Comparative Example 6 investigated by IQ (Image Quality) map.
Figure 3a is a hot-rolled microstructure of Example 3 investigated by IPF (Inverse Pole Figure) map.
Figure 3b is a hot-rolled microstructure of Example 10 investigated by IPF (Inverse Pole Figure) map.
Figure 3c is a hot-rolled microstructure of Comparative Example 1 investigated by IPF (Inverse Pole Figure) map.
Figure 3d is a hot-rolled microstructure of Comparative Example 6 investigated by IPF (Inverse Pole Figure) map.
Figure 4a is a photograph showing the surface microstructure after cold rolling annealing of Example 3.
Figure 4b is a photograph showing the surface microstructure after cold rolling annealing of Example 10.
Figure 4c is a photograph showing the surface microstructure after cold rolling annealing of Comparative Example 1.
Figure 4d is a photograph showing the surface microstructure after cold rolling annealing of Comparative Example 6.

이하에서는 본 발명의 바람직한 실시형태들을 설명한다. 그러나, 본 발명의 실시형태는 여러 가지 다른 형태로 변형될 수 있으며, 본 발명의 기술사상이 이하에서 설명하는 실시형태로 한정되는 것은 아니다. 또한, 본 발명의 실시형태는 당해 기술분야에서 평균적인 지식을 가진 자에게 본 발명을 더욱 완전하게 설명하기 위해서 제공되는 것이다.Preferred embodiments of the present invention are described below. However, the embodiments of the present invention can be modified in many different forms, and the technical spirit of the present invention is not limited to the embodiments described below. In addition, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

본 출원에서 사용하는 용어는 단지 특정한 예시를 설명하기 위하여 사용되는 것이다. 때문에 가령 단수의 표현은 문맥상 명백하게 단수여야만 하는 것이 아닌 한, 복수의 표현을 포함한다. 덧붙여, 본 출원에서 사용되는 "포함하다" 또는 "구비하다" 등의 용어는 명세서 상에 기재된 특징, 단계, 기능, 구성요소 또는 이들을 조합한 것이 존재함을 명확히 지칭하기 위하여 사용되는 것이지, 다른 특징들이나 단계, 기능, 구성요소 또는 이들을 조합한 것의 존재를 예비적으로 배제하고자 사용되는 것이 아님에 유의해야 한다.Terms used in this application are only used to describe specific examples. Therefore, for example, expressions in the singular number include plural expressions unless the context clearly requires them to be singular. In addition, the terms "include" or "have" used in this application are used to clearly indicate that the features, steps, functions, components, or combinations thereof described in the specification exist, but other features It should be noted that it is not intended to be used to preliminarily exclude the presence of any steps, functions, components, or combinations thereof.

한편, 다르게 정의되지 않는 한, 본 명세서에서 사용되는 모든 용어들은 본 발명이 속하는 기술 분야에서 통상의 지식을 가진 자에 의해 일반적으로 이해되는 것과 동일한 의미를 가진 것으로 보아야 한다. 따라서, 본 명세서에서 명확하게 정의하지 않는 한, 특정 용어가 과도하게 이상적이거나 형식적인 의미로 해석되어서는 안 된다. 가령, 본 명세서에서 단수의 표현은 문맥상 명백하게 예외가 있지 않는 한, 복수의 표현을 포함한다.Meanwhile, unless otherwise defined, all terms used in this specification should be regarded as having the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. Accordingly, certain terms should not be interpreted in an overly idealistic or formal sense unless clearly defined herein. For example, in this specification, a singular expression includes a plurality of expressions unless there is a clear exception from the context.

또한, 본 명세서의 "약", "실질적으로" 등은 언급한 의미에 고유한 제조 및 물질 허용오차가 제시될 때 그 수치에서 또는 그 수치에 근접한 의미로 사용되고, 본 발명의 이해를 돕기 위해 정확하거나 절대적인 수치가 언급된 개시 내용을 비양심적인 침해자가 부당하게 이용하는 것을 방지하기 위해 사용된다.In addition, "about", "substantially", etc. in this specification are used at or in the sense of or close to the value when manufacturing and material tolerances inherent in the stated meaning are presented, and are accurate to aid in understanding the present invention. or absolute numbers are used to prevent unfair use by unscrupulous infringers of the stated disclosure.

본 발명에 따른 내리징성이 향상된 페라이트계 스테인리스강은 중량%로, C: 0.001 내지 0.3%, Si: 0.01 내지 1.0%, Mn: 0.1 내지 3.0%, Cr: 10 내지 15%, N: 0.001 내지 0.3%, P: 0.03% 이하, Ni: 1.0% 이하, Cu: 1.0% 이하, Al: 1.0% 이하, Mo: 0.003% 이하, Ti: 1.0% 이하 나머지 Fe 및 기타 불가피한 불순물을 포함The ferritic stainless steel with improved hardening resistance according to the present invention contains, by weight, C: 0.001 to 0.3%, Si: 0.01 to 1.0%, Mn: 0.1 to 3.0%, Cr: 10 to 15%, N: 0.001 to 0.3 %, P: 0.03% or less, Ni: 1.0% or less, Cu: 1.0% or less, Al: 1.0% or less, Mo: 0.003% or less, Ti: 1.0% or less, including remaining Fe and other unavoidable impurities

이하, 각 합금원소의 성분범위를 한정한 이유를 이하에서 서술한다. Hereinafter, the reason for limiting the composition range of each alloy element will be described below.

탄소(C)의 함량은 0.001 내지 0.3%이다.The content of carbon (C) is 0.001 to 0.3%.

C는 침입형 고용강화 원소로서 페라이트계 스테인리스강의 강도를 향상시킨다. C의 함량이 0.001% 미만일 경우, 탄화물(carbide) 생성량을 저하시켜 충분한 강도를 얻을 수 없다. 하지만, C의 함량이 과다하면 강재의 연성, 인성 및 내식성 등을 저하시키므로, 그 상한을 0.3%로 한정하고자 한다.C is an interstitial solid solution strengthening element that improves the strength of ferritic stainless steel. When the content of C is less than 0.001%, sufficient strength cannot be obtained by reducing the amount of carbide produced. However, if the content of C is excessive, the ductility, toughness and corrosion resistance of the steel are reduced, so the upper limit is limited to 0.3%.

규소(Si)의 함량은 0.01 내지 1.0%이다.The content of silicon (Si) is 0.01 to 1.0%.

Si는 제강 시 용강의 탈산을 위해 필수적으로 첨가되는 합금원소이며 강도와 내식성을 향상시키는 동시에, 페라이트 상을 안정하는 원소로 본 발명에서 0.01% 이상 첨가할 수 있다. 다만, 그 함량이 과다할 경우, 연성 및 성형성이 저하되는 문제가 있으므로, 그 상한을 1.0%로 한정하고자 한다.Si is an alloy element that is essentially added for deoxidation of molten steel during steelmaking, improves strength and corrosion resistance, and can be added in an amount of 0.01% or more in the present invention as an element that stabilizes the ferrite phase. However, when the content is excessive, there is a problem in that ductility and formability are lowered, so the upper limit is limited to 1.0%.

망간(Mn)의 함량은 0.1 내지 3.0%이다.The content of manganese (Mn) is 0.1 to 3.0%.

Mn은 오스테나이트상 안정화 원소로, 열간압연중 오스테나이트 핵생성을 유발하여 결정립 미세화를 촉진시킬 수 있다. 다만, 그 함량이 과다할 경우, 내식성을 저하시키고, 용접시 망간계 퓸(fume)이 발생하며, MnS상 석출의 원인이 되어 연신율을 저하시킨다. 따라서, 본 발명에서는 Mn의 함량을 0.1 내지 3.0%로 제어하고자 한다.Mn is an austenite phase stabilizing element, and can induce austenite nucleation during hot rolling to promote crystal grain refinement. However, when the content is excessive, corrosion resistance is lowered, manganese-based fumes are generated during welding, and elongation is reduced by causing MnS phase precipitation. Therefore, in the present invention, the content of Mn is to be controlled to 0.1 to 3.0%.

크롬(Cr)의 함량은 10 내지 15%이다.The content of chromium (Cr) is 10 to 15%.

Cr은 화성 환경에서 부동태 피막을 형성하여 내식성을 향상시키는 원소로서 10% 이상 첨가한다. 그러나 Cr의 함량이 과다할 경우, 열연 시 치밀한 산화 스케일 생성으로 스티킹(Sticking) 결함이 발생하며, 제조원가가 상승하는 문제가 있다. 따라서, 본 발명에서는 Cr 함량의 상한을 15%로 한정하고자 한다.Cr is added in an amount of 10% or more as an element that improves corrosion resistance by forming a passivation film in a igneous environment. However, when the content of Cr is excessive, there is a problem in that a sticking defect occurs due to the formation of a dense oxide scale during hot rolling, and the manufacturing cost increases. Therefore, in the present invention, the upper limit of the Cr content is intended to be limited to 15%.

질소(N)의 함량은 0.001 내지 0.3%이다.The content of nitrogen (N) is 0.001 to 0.3%.

N는 탄소와 마찬가지로 침입형 고용강화 원소로서 페라이트계 스테인리스 강의 강도를 향상시킬 뿐만 아니라, 열간압연 시 오스테나이트상을 석출하여 재결정을 촉진시키는 역할을 하는 원소이다. 다만, 그 함량이 과다할 경우, 강의 연성을 저하시키는 문제가 있다. 따라서, 본 발명에서는 N의 함량을 0.001 내지 0.3%로 제어한다.N, like carbon, is an interstitial solid-solution strengthening element that not only improves the strength of ferritic stainless steel, but also promotes recrystallization by precipitating an austenite phase during hot rolling. However, when the content is excessive, there is a problem of lowering the ductility of the steel. Therefore, in the present invention, the N content is controlled to 0.001 to 0.3%.

인(P)의 함량은 0.03% 이하이다.The content of phosphorus (P) is 0.03% or less.

P은 강 중 불가피하게 함유되는 불순물로, 산세 시 입계 부식을 일으키거나 열간가공성을 저해하는 주요 원인이 되는 원소이므로, 그 함량을 가능한 낮게 제어하는 것이 바람직하다. 따라서, 본 발명에서는 P의 함량은 0.03% 이하로 제어한다.P is an impurity inevitably contained in steel, and since it is an element that causes intergranular corrosion during pickling or inhibits hot workability, it is preferable to control the content thereof as low as possible. Therefore, in the present invention, the content of P is controlled to 0.03% or less.

니켈(Ni)의 함량은 1.0% 이하이다.The content of nickel (Ni) is 1.0% or less.

Ni은 내식성을 향상시키는 효과를 갖는 반면, 다량 첨가하게 되면 소재의 불순물이 증가하여 연신율이 떨어지는 문제가 있다. 또한, Ni은 대표적인 오스테나이트 안정화 원소이나 고가의 원소로서, 제조 원가를 상승시킨다. 따라서, 본 발명에서는 Ni의 함량을 1.0% 이하로 제어한다.While Ni has an effect of improving corrosion resistance, when a large amount is added, there is a problem in that elongation decreases due to an increase in impurities in the material. In addition, Ni is a typical austenite stabilizing element or an expensive element, which increases manufacturing cost. Therefore, in the present invention, the content of Ni is controlled to 1.0% or less.

구리(Cu)의 함량은 1.0% 이하이다.The content of copper (Cu) is 1.0% or less.

Cu는 내식성, 가공성 및 리징성 개선에 효과적인 원소이다. 그러나, 다량 첨가하게 되면 가공성이 저하되는 문제가 있다. 따라서, 본 발명에서 Cu의 함량을 1.0% 이하로 제어한다.Cu is an element effective in improving corrosion resistance, workability and ridging property. However, when a large amount is added, there is a problem in that workability is lowered. Therefore, in the present invention, the content of Cu is controlled to 1.0% or less.

알루미늄(Al)의 함량은 1.0% 이하이다.The content of aluminum (Al) is 1.0% or less.

Al은 페라이트상 안정화 원소로, 강력한 탈산제로써 용강 중 산소의 함량을 낮추는 역할을 한다. 다만, 그 함량이 과다할 경우, 상온 연성을 저하시키며, 비금속 개재물 증가로 인해 냉연 냉연 스트립의 슬리버 결함이 발생함과 동시에 용접성을 열화 시키는 문제가 있다. 따라서, 본 발명에서는 Al의 함량을 1.0% 이하로 제어한다. Al is a ferrite-phase stabilizing element and serves as a strong deoxidizer to lower the oxygen content in molten steel. However, when the content is excessive, room temperature ductility is lowered, and sliver defects of the cold-rolled cold-rolled strip occur due to an increase in non-metallic inclusions, and at the same time, there is a problem of deteriorating weldability. Therefore, in the present invention, the Al content is controlled to 1.0% or less.

몰리브덴(Mo)의 함량은 0.003% 이하이다.The content of molybdenum (Mo) is 0.003% or less.

Mo은 스테인리스강의 내부식성을 향상시키는데 효과적인 원소이다. 하지만, Mo은 고가의 원소로 원료비 상승을 초래하고, 다량 첨가 시 가공성을 저하시킨다. 따라서, 본 발명에서는 Mo의 함량을 0.003% 이하로 제어한다.Mo is an element effective in improving the corrosion resistance of stainless steel. However, Mo is an expensive element that causes an increase in raw material costs and deteriorates workability when added in large amounts. Therefore, in the present invention, the content of Mo is controlled to 0.003% or less.

티타늄(Ti)의 함량은 1.0% 이하이다.The content of titanium (Ti) is 1.0% or less.

Ti은 탄소(C)와 질소(N)와 같은 침입형 원소와 우선적으로 결합하여 석출물(탄질화물)을 형성함으로써, 강 중 고용 C 및 고용 N의 양을 저감하고 강의 내식성 확보에 효과적인 원소이다. 다만, 그 함량이 과다할 경우, 오스테나이트 안정도가 저하되어 미세한 결정립을 얻기 어렵고, 인성이 저하되며, 타이타늄계 개재물이 증가하여 표면결함이 발생하는 문제가 있다. 따라서, 본 발명에서는 티타늄의 함량을 1.0% 이하로 제어한다.Ti is an element effective in reducing the amount of solid solution C and solid solution N in steel and securing corrosion resistance of steel by preferentially combining with interstitial elements such as carbon (C) and nitrogen (N) to form precipitates (carbonitrides). However, when the content is excessive, austenite stability is lowered, making it difficult to obtain fine grains, lowering toughness, and increasing titanium-based inclusions, resulting in surface defects. Therefore, in the present invention, the content of titanium is controlled to 1.0% or less.

본 발명의 나머지 성분은 철(Fe)이다. 다만, 통상의 제조과정에서는 원료 또는 주위 환경으로부터 의도되지 않는 불순물들이 불가피하게 혼입될 수 있으므로, 이를 배제할 수는 없다. 이들 불순물들은 통상의 제조과정의 기술자라면 누구라도 알 수 있는 것이기 때문에 그 모든 내용을 특별히 본 명세서에서 언급하지는 않는다.The remaining component of the present invention is iron (Fe). However, since unintended impurities from raw materials or the surrounding environment may inevitably be mixed in a normal manufacturing process, this cannot be excluded. Since these impurities are known to anyone skilled in the ordinary manufacturing process, not all of them are specifically mentioned in this specification.

또한, 본 발명의 일 실시예에 따른 페라이트계 스테인리스강은 하기 식(1)로 표현되는 γS가 6 이상이다.In addition, in the ferritic stainless steel according to an embodiment of the present invention, γ S represented by the following formula (1) is 6 or more.

식(1): γS = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178Equation (1): γ S = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178

(여기서, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al 및 N는 각 원소의 함량(중량%)을 의미한다)(Here, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al and N mean the content (% by weight) of each element)

γS는(Austenite(gamma-phase) stability)는 고온에서의 최대 오스테나이트 양에 대응하는 오스테나이트상 안정도의 지수이다. 본 발명에서는 오스테나이트상 안정도를 확보함으로써, 열간압연 도중 오스테나이트 상변태를 유도하기 위해, γS 값을 6 이상으로 한정하고자 하였다. 또한, γS 값이 6 미만인 경우에는 페라이트계 스테인리스강의 열연 밴드 조직이 제거되지 않고 잔류하게 되어, 리징 결함이 심하게 발생한다. γ S (Austenite (gamma-phase) stability) is an index of austenite phase stability corresponding to the maximum amount of austenite at high temperatures. In the present invention, in order to induce austenite phase transformation during hot rolling by securing austenite phase stability, the γ S value was intended to be limited to 6 or more. In addition, when the γ S value is less than 6, the hot-rolled band structure of the ferritic stainless steel is not removed and remains, resulting in severe ridging defects.

본 발명은 페라이트계 스테인리스강의 합금성분을 최적화하여 열간압연에서의 오스테나이트 상변태를 유도하였다. 이에 본 발명의 일 실시예에 따른 페라이트계 스테인리스강은 밴드 조직이나 콜로니 조직이 없는 페라이트 단상의 미세한 결정립을 확보할 수 있다. 페라이트 단상 결정립의 크기는 15㎛ 이하일 수 있다.The present invention induced the austenite phase transformation in hot rolling by optimizing the alloy components of the ferritic stainless steel. Accordingly, the ferritic stainless steel according to an embodiment of the present invention can secure fine crystal grains of single phase ferrite without a band structure or colony structure. The size of the ferrite single-phase crystal grains may be 15 μm or less.

다음으로, 본 발명의 다른 실시예에 따른 내리징성이 향상된 페라이트계 스테인리스강의 제조 방법에 대하여 설명한다.Next, a method for manufacturing ferritic stainless steel with improved resistance to hardening according to another embodiment of the present invention will be described.

본 발명의 일 실시예에 따른 페라이트계 스테인리스강의 제조 방법은, 중량%로, C: 0.001 내지 0.3%, Si: 0.01 내지 1.0%, Mn: 0.1 내지 3.0%, Cr: 10 내지 15%, N: 0.001 내지 0.3%, P: 0.03% 이하, Ni: 1.0% 이하, Cu: 1.0% 이하, Al: 1.0% 이하, Mo: 0.003% 이하, Ti: 1.0% 이하 나머지 Fe 및 기타 불가피한 불순물을 포함하고, 하기 식(1)로 표현되는 γS가 6 이상인, 슬라브를 1050 내지 1250℃로 재가열하고, 상기 재가열된 슬라브를 열간압연하고, 상기 열간압연재를 냉간압연 및 냉연소둔하고, 재가열 단계에서, 온도 T에서의 오스테나이트 중량%로 정의되는 γWt(T)가 하기 식(2)를 만족하도록 제어한다.In the manufacturing method of ferritic stainless steel according to an embodiment of the present invention, by weight, C: 0.001 to 0.3%, Si: 0.01 to 1.0%, Mn: 0.1 to 3.0%, Cr: 10 to 15%, N: 0.001 to 0.3%, P: 0.03% or less, Ni: 1.0% or less, Cu: 1.0% or less, Al: 1.0% or less, Mo: 0.003% or less, Ti: 1.0% or less Fe and other unavoidable impurities, The γ S represented by the following formula (1) is 6 or more, the slab is reheated to 1050 to 1250 ° C., the reheated slab is hot rolled, the hot rolled material is cold rolled and cold rolled annealed, and in the reheating step, the temperature γ Wt (T), which is defined as the weight percent of austenite at T, is controlled to satisfy the following equation (2).

식(1): γS = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178Equation (1): γ S = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178

(여기서, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al 및 N는 각 원소의 함량(중량%)을 의미한다)(Here, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al and N mean the content (% by weight) of each element)

식(2): γWt(1200℃) ≥ 19%Equation (2): γ Wt (1200 ° C) ≥ 19%

각 합금원소의 성분범위를 한정한 이유는 상술한 바와 같다.The reason for limiting the composition range of each alloy element is as described above.

γWt(T)(Austenite(gamma-phase) Weight at temperature T)은 재가열 단계에서, 온도 T에서의 오스테나이트 중량%이다. γS가 6 이상을 만족하더라도, 재가열 온도가 높으면 오스테나이트상 안정도가 낮아지게 된다. 오스테나이트상의 안정도가 낮아지게 되면, 열간압연 도중 오스테나이트 상변태가 충분히 일어나지 않아 페라이트 스테인리스강 표면에 열연 밴드조직이 잔류하게 된다.γ Wt (T) (Austenite (gamma-phase) Weight at temperature T) is the weight percent austenite at temperature T, in the reheating phase. Even if γ S satisfies 6 or higher, the stability of the austenite phase decreases when the reheating temperature is high. When the stability of the austenite phase is lowered, the austenite phase transformation does not sufficiently occur during hot rolling, and the hot-rolled band structure remains on the surface of the ferritic stainless steel.

JmatPro를 활용해서 다양한 제어 조건을 검토한 결과, 1200℃의 재가열 온도에서 오스테나이트 중량%를 19% 이상으로 제어할 경우, 열간압연 후 페라이트계 스테인리스강 표면에 미세한 페라이트 결정립을 확보할 수 있었다.As a result of examining various control conditions using JmatPro, it was possible to secure fine ferrite crystal grains on the surface of ferritic stainless steel after hot rolling when the austenite weight% was controlled to 19% or more at a reheating temperature of 1200℃.

또한, 본 발명의 일 실시예에 따르면, 상기 재가열 단계에서, 하기 식(3)을 만족할 수 있다.In addition, according to an embodiment of the present invention, in the reheating step, the following equation (3) may be satisfied.

식(3): γS*γWt(1200℃) ≥ 114Equation (3): γ S * γ Wt (1200 ° C) ≥ 114

식(1) 및 식(2)를 만족하는 동시에 식(1)과 식(2)의 곱을 나타내는 식(3)의 값이 114 이상일 경우, 본 발명에서 목적하는 바와 같이 리징 높이를 10㎛ 이하로 억제할 수 있다.When the value of Equation (3) representing the product of Equations (1) and (2) is 114 or more while satisfying Equations (1) and (2), the ridging height is reduced to 10 μm or less as desired in the present invention. can be suppressed

다음으로, 열간압연중 원하는 최종 두께를 확보하기 위해, 700 내지 950℃에서 마무리 압연(사상압연)이 수행될 수 있다.Next, in order to secure a desired final thickness during hot rolling, finish rolling (finish rolling) may be performed at 700 to 950 ° C.

마무리 압연의 온도를 700℃ 미만으로 유지하면 열연 도중 슬라브의 판 표면에 스티킹(sticking) 결함이 발생한다. 또한, 슬라브를 적정한 두께로 압연하기 위해서는 700℃ 이상에서 열간압연을 해야한다.If the temperature of finish rolling is maintained below 700° C., sticking defects occur on the plate surface of the slab during hot rolling. In addition, in order to roll the slabs to an appropriate thickness, hot rolling should be performed at 700° C. or higher.

반면, 마무리 압연의 온도가 900℃를 초과하면, 상대적으로 크기가 큰 페라이트 결정립이 형성된다. 따라서, 본 발명에서는 열간압연 후 미세한 페라이트 결정립을 만들 수 있도록, 마무리 압연의 온도를 900℃ 이하로 제어한다.On the other hand, when the temperature of finish rolling exceeds 900° C., relatively large ferrite crystal grains are formed. Therefore, in the present invention, the temperature of finish rolling is controlled to 900° C. or less so that fine ferrite crystal grains can be made after hot rolling.

열간압연재는 냉간압연을 위해 표면 산세처리를 한다. 이때, 열연소둔은 생략할 수 있다. 그러나 과도하게 미세한 페라이트 결정립이 형성되거나, 잔류 전위(dislocation)에 기인한 연신율의 저하가 있을 경우, 열간압연재를 열연소둔 할 수 있다.Hot-rolled products undergo surface pickling treatment for cold rolling. At this time, hot rolling annealing may be omitted. However, when excessively fine ferrite crystal grains are formed or there is a decrease in elongation due to residual dislocation, the hot-rolled material may be hot-rolled and annealed.

이에 본 발명의 일 실시예에 따르면, 상기 열간압연 후, 열연소둔하는 단계를 더 포함할 수 있다. 열연소둔은 오스테나이트상이 재생성되지 않고, 열간압연 시 형성된 응력을 제거하기 위해 600 내지 900℃에서 실시하는 것이 바람직하다.Accordingly, according to one embodiment of the present invention, after the hot rolling, a step of hot rolling annealing may be further included. Hot rolling annealing is preferably carried out at 600 to 900 ° C. in order to remove the stress formed during hot rolling without regenerating the austenite phase.

이와 같이, 합금성분 및 성분 관계식뿐만 아니라 재가열 및 열간압연 공정을 최적화함으로써 페라이트 단상의 미세한 결정립을 도출하여 페라이트계 스테인리스강의 표면특성을 확보할 수 있다.In this way, by optimizing the reheating and hot rolling processes as well as the alloy components and component relations, it is possible to secure the surface characteristics of the ferritic stainless steel by deriving the fine crystal grains of the ferrite single phase.

이하, 실시예를 통하여 본 발명을 보다 구체적으로 설명하고자 한다. 다만, 하기의 실시예는 본 발명을 예시하여 보다 상세하게 설명하기 위한 것일 뿐, 본 발명의 권리범위를 한정하기 위한 것이 아니라는 점에 유의할 필요가 있다. 본 발명의 권리범위는 특허청구범위에 기재된 사항과 이로부터 합리적으로 유추되는 사항에 의해 결정되는 것이기 때문이다.Hereinafter, the present invention will be described in more detail through examples. However, it should be noted that the following examples are only for illustrating the present invention in more detail, and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the claims and the matters reasonably inferred therefrom.

{실시예}{Example}

하기 표 1에 나타낸 다양한 합금 성분 범위에 대하여, 연주 공정(Continuous Casting)으로 슬라브를 제조하고, 1,050 내지 1,200℃에서 재가열하였다. 다음으로, 상기 재가열된 슬라브를 700 내지 950℃의 온도로 마무리 압연하였다.For the various alloy composition ranges shown in Table 1 below, slabs were prepared by continuous casting and reheated at 1,050 to 1,200 ° C. Next, the reheated slab was finish-rolled at a temperature of 700 to 950 ° C.

구분division 합금 조성alloy composition CC SiSi MnMn PP CrCr NiNi CuCu MoMo AlAl TiTi NbNb NN 실시예 1Example 1 0.0110.011 0.240.24 0.480.48 0.0240.024 11.211.2 0.780.78 00 00 0.020.02 0.180.18 00 0.010.01 실시예 2Example 2 0.0070.007 0.230.23 0.50.5 0.0230.023 1111 0.790.79 0.190.19 00 0.0170.017 0.170.17 00 0.010.01 실시예 3Example 3 0.0070.007 0.150.15 0.90.9 0.020.02 10.610.6 00 0.30.3 00 00 0.150.15 00 0.0080.008 실시예 4Example 4 0.0110.011 0.20.2 1One 0.020.02 10.810.8 00 0.310.31 00 00 0.220.22 00 0.010.01 실시예 5Example 5 0.0110.011 0.150.15 1One 0.020.02 10.610.6 00 0.310.31 00 00 0.150.15 00 0.010.01 실시예 6Example 6 0.0070.007 0.10.1 0.90.9 0.020.02 10.510.5 00 0.30.3 00 00 0.1350.135 00 0.0080.008 실시예 7Example 7 0.0110.011 0.10.1 1One 0.020.02 10.510.5 00 0.310.31 00 00 0.1350.135 00 0.010.01 실시예 8Example 8 0.0050.005 0.10.1 0.820.82 0.020.02 10.510.5 00 0.210.21 00 00 0.1350.135 00 0.0040.004 실시예 9Example 9 0.0050.005 0.150.15 0.820.82 0.020.02 10.610.6 00 0.210.21 00 00 0.150.15 00 0.0040.004 실시예 10Example 10 0.0070.007 0.20.2 0.90.9 0.020.02 14.114.1 00 0.40.4 00 00 00 00 0.0570.057 비교예 1Comparative Example 1 0.0060.006 0.550.55 0.30.3 0.0220.022 11.211.2 00 00 00 00 0.20.2 00 0.0080.008 비교예 2Comparative Example 2 0.0060.006 0.520.52 0.150.15 0.0240.024 11.111.1 0.80.8 00 00 0.0260.026 0.190.19 00 0.00720.0072 비교예 3Comparative Example 3 0.0050.005 0.20.2 0.820.82 0.020.02 10.810.8 00 0.210.21 00 00 0.220.22 00 0.0040.004 비교예 4Comparative Example 4 0.0070.007 0.20.2 0.90.9 0.020.02 10.810.8 00 0.30.3 00 00 0.220.22 00 0.0080.008 비교예 5Comparative Example 5 0.0070.007 0.850.85 0.30.3 0.020.02 1515 00 00 00 00 0.130.13 0.40.4 0.0060.006 비교예 6Comparative Example 6 0.0070.007 0.20.2 4.64.6 0.020.02 14.114.1 00 22 00 00 0.20.2 00 0.0080.008 비교예 7Comparative Example 7 0.0070.007 0.10.1 22 0.020.02 14.114.1 00 2.52.5 00 0.20.2 00 00 0.0080.008

상기 열간압연재를 산세처리하고, 1.0t 이하의 두께까지 냉간압연한 후 오스테나이트상이 재생성되지 않도록 700 내지 900℃에서 냉연소둔하였다. 그 후 냉연소둔재를 압연 방향으로 15% 인장하여 표면조도기로 리징 굴곡의 높이를 측정하였다. 하기 표 2는 상기 실시예 및 비교예의 γS, γWt(1200℃), γS*γWt(1200℃) 및 리징 높이(㎛)를 나타낸 값이다.The hot-rolled material was pickled, cold-rolled to a thickness of 1.0t or less, and then cold-rolled and annealed at 700 to 900° C. to prevent regeneration of the austenite phase. After that, the cold-rolled annealed material was stretched by 15% in the rolling direction, and the height of the ridging curve was measured with a surface roughness machine. Table 2 below shows values of γ S, γ Wt (1200 ° C), γ S * γ Wt (1200 ° C) and ridging height (μm) of the above examples and comparative examples.

구분division γS γ S γWt(1200℃)
(%)γ Wt (1200℃)
(%) γS*γWt(1200℃)γ S * γ Wt (1200℃) 리징 높이
(㎛)leasing height
(μm) 실시예 1Example 1 13.613.6 3333 450.1450.1 6.36.3 실시예 2Example 2 17.117.1 4343 736.8736.8 4.44.4 실시예 3Example 3 14.314.3 3131 441.8441.8 6.26.2 실시예 4Example 4 12.712.7 2222 280.3280.3 8.68.6 실시예 5Example 5 21.121.1 4242 884.9884.9 4.84.8 실시예 6Example 6 18.218.2 3939 709.2709.2 5.25.2 실시예 7Example 7 25.025.0 5151 1275.31275.3 4.14.1 실시예 8Example 8 10.510.5 2626 274.2274.2 8.18.1 실시예 9Example 9 6.66.6 1919 125.6125.6 9.39.3 실시예 10Example 10 8.48.4 2323 192.05192.05 5.65.6 비교예 1Comparative Example 1 -22.1-22.1 00 0.00.0 22.922.9 비교예 2Comparative Example 2 -4.5-4.5 88 -36.2-36.2 20.520.5 비교예 3Comparative Example 3 -1.7-1.7 22 -3.4-3.4 21.721.7 비교예 4Comparative Example 4 5.95.9 1111 65.165.1 17.617.6 비교예 5Comparative Example 5 -93.3-93.3 00 0.00.0 23.523.5 비교예 6Comparative Example 6 15.615.6 1818 280.8280.8 13.813.8 비교예 7Comparative Example 7 -7.2-7.2 2424 -172.8-172.8 12.412.4

표 2를 살펴보면, 실시예 1 내지 10은 γS가 6 이상이며, γWt(1200℃)가 19% 이상이고, γS*γWt(1200℃)가 114 이상을 만족한다. 이에 따라, 실시예 1 내지 10은 리징 높이가 10㎛ 이하로 표면 품질이 양호하게 도출되었다.Referring to Table 2, Examples 1 to 10 have γ S of 6 or more, γ Wt (1200 ° C.) of 19% or more, and γ S * γ Wt (1200 ° C.) of 114 or more. Accordingly, in Examples 1 to 10, the ridging height was 10 μm or less, and the surface quality was good.

반면에, 비교예 1은 γS가 -22.1로 6 미만이며, γWt(1200℃)가 0%로 19% 미만이고, γS*γWt(1200℃)가 0으로 114 미만이다. 이에 따라, 비교예 1은 높이가 22.9㎛인 리징 결함이 발생했다.On the other hand, in Comparative Example 1, γ S is -22.1 and less than 6, γ Wt (1200 ° C) is 0% and less than 19%, and γ S * γ Wt (1200 ° C) is 0 and less than 114. Accordingly, in Comparative Example 1, a ridging defect having a height of 22.9 μm occurred.

또한, 비교예 2 내지 5는 γS가 6 미만이며, γS*γWt(1200℃)가 19% 미만이고, γS*γWt(1200℃)가 114 미만이다. 이에 따라, 비교예 2 내지 5는 모두 10㎛ 보다 큰 리징 결함이 발생했다.In Comparative Examples 2 to 5, γ S is less than 6, γ S * γ Wt (1200 ° C.) is less than 19%, and γ S * γ Wt (1200 ° C.) is less than 114. Accordingly, all of Comparative Examples 2 to 5 had ridging defects larger than 10 µm.

비교예 6은 γS가 15.6으로 본 발명에서 제시하는 6 이상을 만족하고, γS*γWt(1200℃)가 114 이상인 280.8의 값을 가진다. 그러나, 비교예 6은 γWt(1200℃)가 18%로 19% 미만의 값을 가져, 10㎛ 보다 큰 13.8㎛의 리징 결함이 발생했다.In Comparative Example 6, γ S is 15.6, which satisfies 6 or more suggested in the present invention, and γ S * γ Wt (1200 ° C) has a value of 280.8, which is 114 or more. However, in Comparative Example 6, γ Wt (1200° C.) was 18% and less than 19%, resulting in ridging defects of 13.8 μm larger than 10 μm.

비교예 7은 γWt(1200℃)가 24%로 19% 이상이다. 그러나, 비교예 7은 γS가 -7.2로 6 미만이며, γS*γWt(1200℃)가 -172.8로 114 미만이다. 이에 따라, 비교에 7은 10㎛ 보다 큰 12.4㎛의 리징 결함이 발생했다.In Comparative Example 7, γ Wt (1200 ° C.) is 24%, which is 19% or more. However, in Comparative Example 7, γ S is -7.2 and less than 6, and γ S * γ Wt (1200°C) is -172.8 and less than 114. Accordingly, in Comparative Example 7, a ridging defect of 12.4 μm, which is larger than 10 μm, occurred.

개시된 실시예 및 비교예를 통해, 본 발명이 제시한 γS, γWt(1200℃) 및 γS*γWt(1200℃)의 범위를 만족하는 경우 10㎛ 이하의 리징 결함이 발생하는 것을 알 수 있었다.Through the disclosed Examples and Comparative Examples, it can be seen that when the ranges of γ S , γ Wt (1200 ° C.) and γ S * γ Wt (1200 ° C.) proposed by the present invention are satisfied, ridging defects of 10 μm or less occur. could

하기 표 3은 상기 실시예 3, 실시예 10, 비교예 1 및 비교예 6에 대해서, 열간압연 후 밴드 조직 관찰 여부와 냉연 소둔 후 밴드 조직 관찰 여부 및 페라이트 결정립 크기를 측정한 값이다.Table 3 below shows the measured values of the band structure observed after hot rolling and the band structure observed after cold rolling annealing and ferrite crystal grain sizes for Example 3, Example 10, Comparative Example 1 and Comparative Example 6.

구분division 열간 압연 후
밴드 조직 관찰 여부after hot rolling
Observation of band organization 냉연 소둔 후
밴드 조직 관찰 여부after cold annealing
Observation of band organization 냉연 소둔 후
페라이트 결정립 크기after cold annealing
ferrite grain size 비고note 실시예 3Example 3 XX XX 10.8㎛10.8㎛ 도 2a 및 도 3a2a and 3a 실시예 10Example 10 XX XX 11.2㎛11.2㎛ 도 2b 및 도 3b2b and 3b 비교예 1Comparative Example 1 OO XX 35.1㎛35.1㎛ 도 2c 및 도 3c2c and 3c 비교예 6Comparative Example 6 OO XX 18.9㎛18.9㎛ 도 2d 및 도 3d2d and 3d

표 3 및 도 2a ~ 2d를 살펴보면, 실시예 3 및 실시예 10은 밴드 구조가 관찰되지 않고, 미세한 페라이트 결정립이 고르게 분포되어 있다. 반면에 비교예 1 및 비교예 6은 열간압연 후 잔류해 있는 밴드 구조가 관찰됐다.Looking at Table 3 and FIGS. 2a to 2d, in Examples 3 and 10, no band structure was observed, and fine ferrite grains were evenly distributed. On the other hand, in Comparative Example 1 and Comparative Example 6, a band structure remaining after hot rolling was observed.

표 3 및 도 4a ~ 4d를 살펴보면, 실시예 3의 페라이트 결정립 크기는 10.8㎛이고, 실시예 10의 페라이트 결정립 크기는 11.2㎛이다. 반면, 비교예 1의 페라이트 결정립 크기는 35.1㎛이고, 비교예 6의 페라이트 결정립 크기는 18.9㎛이다.Referring to Table 3 and FIGS. 4a to 4d, the ferrite grain size of Example 3 is 10.8 μm, and the ferrite grain size of Example 10 is 11.2 μm. On the other hand, the ferrite grain size of Comparative Example 1 is 35.1 μm, and the ferrite grain size of Comparative Example 6 is 18.9 μm.

냉연소둔 후 실시예 3 및 실시예 10 과 비교예 1 및 비교예 6 모두 표면에서 밴드 조직은 관찰되지 않았다. 그러나 비교예 1 및 비교예 6의 경우에는, 페라이트 결정립의 크기가 15㎛ 이상으로, 실시예에 비해 조대하게 도출되었음을 확인할 수 있다.No band structure was observed on the surface of Examples 3 and 10 and Comparative Examples 1 and 6 after cold annealing. However, in the case of Comparative Example 1 and Comparative Example 6, it can be confirmed that the size of the ferrite grains was greater than 15 μm, and coarser than that of Examples.

개시된 실시예에 따르면, 합금성분 및 성분 관계식뿐만 아니라, 재가열 및 열간압연 조건을 최적화함으로써, 표면에 밴드 조직이나 콜로니 조직이 발현되지 않고, 리징 높이를 10㎛ 이하로 억제하여, 페라이트계 스테인리스강의 균일한 표면 품질을 확보할 수 있다.According to the disclosed embodiment, by optimizing not only alloy components and component relations, but also reheating and hot rolling conditions, band structures or colony structures are not expressed on the surface, and the ridging height is suppressed to 10 μm or less, so that ferritic stainless steel is uniform. surface quality can be ensured.

상술한 바에 있어서, 본 발명의 예시적인 실시예들을 설명하였지만, 본 발명은 이에 한정되지 않으며 해당 기술 분야에서 통상의 지식을 가진 자라면 다음에 기재하는 청구범위의 개념과 범위를 벗어나지 않는 범위 내에서 다양한 변경 및 변형이 가능함을 이해할 수 있을 것이다.In the foregoing, exemplary embodiments of the present invention have been described, but the present invention is not limited thereto, and those skilled in the art within the scope that does not deviate from the concept and scope of the claims described below. It will be appreciated that many changes and modifications are possible.

Claims (7)

중량%로, C: 0.001 내지 0.3%, Si: 0.01 내지 1.0%, Mn: 0.1 내지 3.0%, Cr: 10.5 내지 14.1%, N: 0.001 내지 0.3%, P: 0.03% 이하, Ni: 1.0% 이하, Cu: 1.0% 이하, Al: 1.0% 이하, Mo: 0.003% 이하, Ti: 1.0% 이하 나머지 Fe 및 기타 불가피한 불순물을 포함하고,
하기 식(1)로 표현되는 γS가 6 이상 25 이하인, 내리징성이 향상된 페라이트계 스테인리스강.
식(1): γS = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178
(여기서, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al 및 N는 각 원소의 함량(중량%)을 의미한다)In weight percent, C: 0.001 to 0.3%, Si: 0.01 to 1.0%, Mn: 0.1 to 3.0%, Cr: 10.5 to 14.1%, N: 0.001 to 0.3%, P: 0.03% or less, Ni: 1.0% or less , Cu: 1.0% or less, Al: 1.0% or less, Mo: 0.003% or less, Ti: 1.0% or less, including the remaining Fe and other unavoidable impurities,
A ferritic stainless steel with improved resistance to hardening, wherein γ S represented by the following formula (1) is 6 or more and 25 or less.
Equation (1): γ S = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178
(Here, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al and N mean the content (% by weight) of each element) 청구항 1에 있어,
페라이트 결정립 크기가 15㎛ 이하인 내리징성이 향상된 페라이트계 스테인리스강.In claim 1,
Ferritic stainless steel with improved hardening resistance with a ferrite grain size of 15㎛ or less. 청구항 1에 있어,
1.0mm 이하의 두께에서 15% 인장한 후 측정한 리징 높이(Wt)가 10㎛ 이하인 내리징성이 향상된 페라이트계 스테인리스강.In claim 1,
Ferritic stainless steel with improved ridging resistance with a ridging height (Wt) of 10㎛ or less, measured after 15% elongation at a thickness of 1.0mm or less. 중량%로, C: 0.001 내지 0.3%, Si: 0.01 내지 1.0%, Mn: 0.1 내지 3.0%, Cr: 10.5 내지 14.1%, N: 0.001 내지 0.3%, P: 0.03% 이하, Ni: 1.0% 이하, Cu: 1.0% 이하, Al: 1.0% 이하, Mo: 0.003% 이하, Ti: 1.0% 이하 나머지 Fe 및 기타 불가피한 불순물을 포함하고, 하기 식(1)로 표현되는 γS가 6 이상 25 이하인, 슬라브를 1050 내지 1250℃로 재가열하는 단계;
상기 재가열된 슬라브를 열간압연 하는 단계; 및
상기 열간압연재를 냉간압연하고, 냉연소둔하는 단계;를 포함하고,
재가열 단계에서, 온도 T에서의 오스테나이트 중량%로 정의되는 γWt(T)가 하기 식(2)를 만족하도록 제어하는, 내리징성이 향상된 페라이트계 스테인리스강의 제조방법.
식(1): γS = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178
(여기서, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al 및 N는 각 원소의 함량(중량%)을 의미한다)
식(2): γWt(1200℃) ≥ 19%In weight percent, C: 0.001 to 0.3%, Si: 0.01 to 1.0%, Mn: 0.1 to 3.0%, Cr: 10.5 to 14.1%, N: 0.001 to 0.3%, P: 0.03% or less, Ni: 1.0% or less , Cu: 1.0% or less, Al: 1.0% or less, Mo: 0.003% or less, Ti: 1.0% or less, including the remaining Fe and other unavoidable impurities, and γ S represented by the following formula (1) is 6 or more and 25 or less, Reheating the slab to 1050 to 1250 ° C;
hot rolling the reheated slab; and
Including; cold rolling and cold rolling annealing the hot rolled material,
In the reheating step, γ Wt (T), defined as austenite weight% at a temperature T, is controlled to satisfy the following formula (2), a method for producing ferritic stainless steel with improved hardening resistance.
Equation (1): γ S = 900C-30Si+12Mn+23Ni-17Cr-12Mo+12Cu-49Ti-52Al+950N+178
(Here, C, Si, Mn, Ni, Cr, Mo, Cu, Ti, Al and N mean the content (% by weight) of each element)
Equation (2): γ Wt (1200 ° C) ≥ 19% 청구항 4에 있어,
상기 재가열 단계에서, 하기 식(3)을 만족하는, 내리징성이 향상된 페라이트계 스테인리스강의 제조방법.
식(3): γS*γWt(1200℃) ≥ 114In claim 4,
In the reheating step, a method for producing a ferritic stainless steel with improved resistance to hardening, which satisfies the following formula (3).
Equation (3): γ S * γ Wt (1200 ° C) ≥ 114 청구항 4에 있어,
상기 열간압연은 700 내지 950℃의 온도로 마무리 압연하는 단계를 포함하는, 내리징성이 향상된 페라이트계 스테인리스강의 제조방법.In claim 4,
The hot rolling is a method for producing ferritic stainless steel with improved resistance to hardening, comprising the step of finishing rolling at a temperature of 700 to 950 ° C. 청구항 4에 있어,
상기 열간압연 후, 600 내지 900℃에서 열연 소둔하는 단계를 더 포함하는, 내리징성이 향상된 페라이트계 스테인리스강 제조방법.In claim 4,
After the hot rolling, a method for producing ferritic stainless steel with improved resistance to hardening, further comprising the step of hot rolling annealing at 600 to 900 ° C.
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JP2004197197A (en) * 2002-12-20 2004-07-15 Jfe Steel Kk Ferritic stainless steel sheet having excellent workability and ridging resistance, and its production method
KR100467719B1 (en) 2000-12-08 2005-01-24 주식회사 포스코 Method of producing ferritic stainless steel sheets having softning, anti-ridging property and excellent spinning formability
WO2015099459A1 (en) 2013-12-24 2015-07-02 (주)포스코 Ferritic stainless steel with improved formability and ridging resistance, and manufacturing method therefor

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JP2772237B2 (en) * 1994-03-29 1998-07-02 川崎製鉄株式会社 Method for producing ferritic stainless steel strip with small in-plane anisotropy
JP4003821B2 (en) * 1999-03-05 2007-11-07 日本冶金工業株式会社 Method for producing ferritic stainless steel sheet with excellent ridging resistance
KR100406406B1 (en) 1999-08-24 2003-11-19 주식회사 포스코 Process for producing hot rolled ferrite stainless steel having superior ridging resistance with preventing from sticking
KR101522077B1 (en) * 2012-12-20 2015-05-20 주식회사 포스코 Manufacturing method of ferritic stainless steel sheet with excellent ridging resistance

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KR100467719B1 (en) 2000-12-08 2005-01-24 주식회사 포스코 Method of producing ferritic stainless steel sheets having softning, anti-ridging property and excellent spinning formability
JP2004197197A (en) * 2002-12-20 2004-07-15 Jfe Steel Kk Ferritic stainless steel sheet having excellent workability and ridging resistance, and its production method
WO2015099459A1 (en) 2013-12-24 2015-07-02 (주)포스코 Ferritic stainless steel with improved formability and ridging resistance, and manufacturing method therefor

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